ViewSonic P774B-2NT Series, Service Manual

Page: 20 / 45

19
6-9 POWER SUPPLY TROUBLE SHOOTING CHART
BEFORE CHECK SW.REG. PLEASE REFER TO THE POWER SUPPLY BLOCK DIAGRAM
POWER SUPPLY OUTPUT: (A) VARIABLE OUTPUT : 58V - 145V
(DEPENDING EPENDING UPON H.SYNC FREQUENCY)
(B) CONSTANT OUTPUT : 6.3V, 14V, -12V, 78V
BEAD SET ABNORMAL VARIABLE OUTPUT
NG
OK
NG
OK
OK
NG
NG
OK
OK
NG
OK
NG
YES
NO
CHECK BRIDGE
RECTIFIED CIRCUIT
CHECK START C.K.T
R939, D912, D911, R930
CHECK IC401
CHECK D919
CHECK Q911
Q911 FAILURE
CHECK IC901
CHECK AC LINE
VOLT 120V OR 220V
CHECK F901, SW901
CHECK LINE RECTIFIED
& SMOOTHED VOLT
CHECK T901 O/P
MAKE SURE THAT
THE VARIABLE
OUTPUT IS NOT SHORTED
OK
PIN 14, 15, 16, 28, B+
DRIVER
IC401 29(ABOUT 11.5V)
CHECK 55.5V, 12.3V, 6.3V
CIRCUIT OUTPUT
CHECK THE 55.5V